U.S. patent number 10,284,062 [Application Number 15/151,853] was granted by the patent office on 2019-05-07 for method for manufacturing workpiece and method for manufacturing laminated core.
This patent grant is currently assigned to MITSUI HIGH-TEC, INC.. The grantee listed for this patent is Mitsui High-tec, Inc.. Invention is credited to Yusuke Hasuo, Masahiro Izumi.
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United States Patent |
10,284,062 |
Hasuo , et al. |
May 7, 2019 |
Method for manufacturing workpiece and method for manufacturing
laminated core
Abstract
This disclosure relates to a method for manufacturing a
workpiece for a segmented laminated core. This method includes (A)
feeding a plate for processing drawn from a roll thereof to a
progressive die and (B) stamping out a workpiece in the progressive
die, the workpiece including a plurality of pieces aligned in the
circumferential direction with a circumferential part. At the step
(B), an overall portion configured to be each piece of the
workpiece is displaced in the thickness direction of the plate for
processing, with portions on both sides of the piece being fixed,
to form at least one cutting line across a region configured to be
the circumferential part.
Inventors: |
Hasuo; Yusuke (Kitakyushu,
JP), Izumi; Masahiro (Kitakyushu, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsui High-tec, Inc. |
Yahatanishi-ku, Kitakyushu-shi |
N/A |
JP |
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Assignee: |
MITSUI HIGH-TEC, INC.
(Kitakyushu-Shi, Fukuoka, JP)
|
Family
ID: |
55910887 |
Appl.
No.: |
15/151,853 |
Filed: |
May 11, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160336840 A1 |
Nov 17, 2016 |
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Foreign Application Priority Data
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May 12, 2015 [JP] |
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2015-097222 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21D
35/001 (20130101); H02K 15/024 (20130101); H02K
15/03 (20130101); H02K 1/148 (20130101); H02K
15/022 (20130101); Y10T 29/49078 (20150115) |
Current International
Class: |
H01F
7/04 (20060101); H02K 15/02 (20060101); B21D
35/00 (20060101); H02K 15/03 (20060101) |
Field of
Search: |
;29/609,596,598,605,606,604
;310/71,216.004,216.011,216.059,216.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2000-201457 |
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Jul 2000 |
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JP |
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2005-318763 |
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Nov 2005 |
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JP |
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2005-318764 |
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Nov 2005 |
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JP |
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2012-005155 |
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Jan 2012 |
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JP |
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Other References
Extended European Search Report for EP App No. 16168309.9 dated
Oct. 12, 2016, 9 pgs. cited by applicant.
|
Primary Examiner: Phan; Thiem D
Attorney, Agent or Firm: Procopio, Cory, Hargreaves &
Savitch LLP
Claims
What is claimed is:
1. A method for manufacturing a segmented workpiece, the method
comprising: (A) feeding a plate for processing drawn from a roll
thereof to a progressive die; and (B) stamping out a workpiece in
the progressive die, the workpiece including a plurality of pieces
aligned in a circumferential direction with a circumferential part,
wherein the stamping comprises: forming a first cutting line and a
second cutting line to define a first portion that is configured to
become a piece of the plurality of pieces, the forming including:
fixing, in a thickness direction, a second portion configured to
become an adjacent piece of the plurality of pieces, and a third
portion configured to become another adjacent piece of the
plurality of pieces, the first portion being disposed between the
second portion and the third portion in a circumferential
direction, and displacing the first portion in the thickness
direction while the second portion and the third portion remain
fixed.
2. The method according to claim 1, wherein a bending line radially
outside or radially inside the circumferential part and the two
cutting lines are formed by cutting-and-bending processing.
3. The method according to claim 1, wherein the two cutting lines
are formed by stamping.
4. The method according to claim 1, wherein the (B) includes,
before forming the circumferential part by performing stamping at
an outer circumference of the workpiece, the successive steps of:
(b-1) forming an inner opening radially inside the circumferential
part; and (b-2) forming the two cutting lines on the region
configured to be the circumferential part.
5. The method according to claim 4, further comprising: (b-1a)
forming an outer opening radially outside the inner opening.
6. The method according to claim 1, wherein the (B) includes the
step of returning the piece having been displaced in the thickness
direction of the plate for processing to an original position.
7. A method for manufacturing a laminated core, the method
comprising the steps of: producing workpieces by the method
according to claim 1; and fastening the workpieces together to
obtain a laminated core.
8. The method according to claim 1, wherein the two cutting lines
are formed simultaneously by a single displacement, and the
displacing is performed once for every two pieces that are formed.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority
from Japanese Patent Application No. 2015-097222, filed May 12,
2015, the entire contents of which are incorporated herein by
reference.
BACKGROUND
1. Field
This disclosure relates to a method for manufacturing a workpiece
for a laminated core and a method for manufacturing a laminated
core.
A laminated core is a component of a motor. The laminated core is
formed by stacking a plurality of magnetic steel sheets
(workpieces) each of which is processed in a predetermined shape
and fastening the sheets together. The motor includes a rotor and a
stator each of which contains a laminated core, and is produced
through a step of winding a coil on the stator and a step of
attaching a shaft to the rotor, for example. Motors incorporating
laminated cores have been conventionally used as driving sources
for refrigerators, air conditioners, hard disc drives, and electric
tools, for example, and are also used as driving sources for hybrid
cars these days.
2. Related Background Art
Japanese Patent No. 4472417 discloses a method for manufacturing a
segmented laminated core. Referring to FIG. 7 and FIG. 8 in
Japanese Patent No. 4472417, slit lines L are formed by
cutting-and-bending processing and push-back (see paragraphs [0028]
to [0032] in Japanese Patent No. 4472417).
SUMMARY
This disclosure relates to a method for manufacturing a segmented
workpiece. This manufacturing method includes (A) feeding a plate
for processing drawn from a roll thereof to a progressive die and
(B) stamping out a workpiece in the progressive die, the workpiece
including a plurality of pieces aligned in the circumferential
direction with a circumferential part. At the above-described step
(B), an overall portion configured to be each piece of the
workpiece is displaced in a thickness direction of the plate for
processing, with portions on both sides of the piece being fixed,
to form at least one cutting line across a region configured to be
the circumferential part.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of one example of a segmented
laminated core for a stator;
FIG. 2 is a plan view of a segmented workpiece constituting the
laminated core depicted in FIG. 1;
FIG. 3 is a schematic diagram illustrating one example of a
stamping device;
FIGS. 4A to 4F are plan views for illustrating an overall strip
layout for forming cutting lines by cutting-and-bending
processing;
FIGS. 5A to 5C are enlarged plan views of FIGS. 4A to 4C (the first
half of the strip layout), respectively;
FIGS. 6A to 6C are enlarged plan views of FIGS. 4D to 4F (the
latter half of the strip layout), respectively;
FIG. 7 is a plan view of an opening formed on a bending line;
FIG. 8A is a plan view in which a dashed line indicates the shape
of a punch configured to contact part of a portion to be displaced
in the thickness direction of a plate for processing, and FIG. 8B
is a plan view in which a dashed line indicates the shape of a
punch configured to contact the overall portion to be displaced in
the thickness direction of the plate for processing;
FIGS. 9A to 9E are plan views for illustrating an overall strip
layout for forming cutting lines by stamping;
FIGS. 10A to 10C are enlarged plan views of FIGS. 9A to 9C (the
first half of the strip layout), respectively;
FIGS. 11A and 11B are enlarged plan views of FIGS. 9D and 9E (the
latter half of the strip layout), respectively;
FIG. 12 is a plan view for illustrating another example in which
cutting lines are formed by stamping;
FIG. 13A is a sectional view for illustrating a state before
forming the cutting lines by stamping, and FIG. 13B is a sectional
view for illustrating a state after forming the cutting lines by a
descent of a die;
FIG. 14 is a plan view of a laminated core including eight core
pieces each having six tooth parts; and
FIG. 15 is a plan view of a segmented workpiece including nine (an
odd number of) pieces.
DETAILED DESCRIPTION
Hereinafter, a plurality of embodiments of the present invention
will be described with reference to the accompanying drawings. In
the description of the drawings, the same elements will be
designated by the same reference numerals and a duplicate
description thereof will be omitted. The drawings and the related
technologies are provided in order to describe the embodiments of
the present invention, and do not limit the scope of the present
invention.
<Laminated Core and Workpiece>
FIG. 1 is a perspective view of a segmented laminated core S
constituting a stator. The shape of the laminated core S is
substantially cylindrical, and an opening Sa positioned in its
central part is used for arranging a rotor (not depicted). A
plurality of workpieces MS constitute the laminated core S. The
laminated core S has a circumferential yoke part Sy and tooth parts
St extending from the inner periphery of the yoke part Sy toward
the center. Depending on the usage and performance of the motor,
the width of the yoke part Sy is about 2 to 40 millimeters. The
laminated core S includes a total of 12 core pieces Sd each having
one tooth part St. Thus, the laminated core S has 12 tooth parts St
in total. Spaces called "slots" (hereinafter referred to as "slots
Sl") are formed between adjacent tooth parts St.
The laminated core S is produced by stacking the workpieces MS one
of which is depicted in FIG. 2 and fastening the workpieces
together. Any method for fastening the workpieces MS together is
applicable. For example, the workpieces may be fastened to each
other by swaging, welding, adhesive, or a resin material.
Conventionally, swaging and welding have been widely used in view
of cost and work efficiency. Alternatively, when higher priorities
are given to greater torque and lower iron loss of a motor, instead
of swaging or welding, a resin material or adhesive may be used.
The laminated core S may be obtained by disposing a
temporarily-interlocking portion to fasten the workpieces MS to
each other, and finally removing the temporarily-interlocking
portion from the laminate. The "temporarily-interlocking portion"
is a swaged portion used for temporarily integrating a plurality of
workpieces produced by stamping, and then removed in a process of
producing a product (laminated core).
When the temporarily-interlocking portion is not disposed on the
workpieces MS, the shape of each workpiece MS in plan view is the
same as that of the laminated core S, as depicted in FIG. 2. The
workpiece MS includes a through hole Ma constituting the opening
Sa, a circumferential part My constituting the yoke part Sy, and
protruding parts Mt constituting the tooth parts St. The workpiece
MS includes a total of 12 pieces Md each having one protruding part
Mt. Thus, the workpiece has 12 protruding parts Mt in total. Slot
holes Ml constituting the slots Sl are formed between adjacent
protruding parts Mt.
The circumferential part My of the workpiece MS has a plurality of
cutting lines Mc formed across the circumferential part My. Each
cutting line Mc is formed so that a projection will fit into a
depression. The shape of the cutting line Mc is not limited to the
shape having the depression and the projection as depicted in FIGS.
1 and 2 and may be a linear shape (that may tilt with respect to
the radial direction), a curved shape, or a combination
thereof.
<Stamping Device>
FIG. 3 is a schematic diagram illustrating one example of a
stamping device for producing the workpieces MS constituting the
laminated core S by stamping. The stamping device 100 depicted in
FIG. 3 includes an uncoiler 110 on which a roll C is mounted, a
feeder 130 configured to feed a magnetic steel sheet (hereinafter
referred to as "sheet W") drawn from the roll C, a progressive die
140 configured to perform stamping on the sheet W, and a press
machine 120 configured to cause the progressive die 140 to
operate.
The uncoiler 110 rotatably holds the roll C. The length of the
magnetic steel sheet constituting the roll C is 500 to 10,000
meters, for example. The thickness of the magnetic steel sheet
constituting the roll C may be about 0.1 to 0.5 millimeter, or may
be about 0.1 to 0.3 millimeter from a viewpoint of achieving more
excellent magnetic properties of the laminated core S. The width of
the magnetic steel sheet (sheet W) may be about 50 to 500
millimeters.
The feeder 130 has a pair of rollers 130a and 130b that sandwich
the sheet W from above and below. The sheet W is fed into the
progressive die 140 via the feeder 130. The progressive die 140 is
a device configured to serially perform stamping,
cutting-and-bending processing, and push-back, for example, on the
sheet W.
<Method for Manufacturing Laminated Core>
A method for manufacturing the laminated core S will be described
next. The laminated core S is produced through a process of
producing the workpieces MS (steps (A) and (B) below) and a process
of producing the laminated core S from the workpieces MS (step (C)
below). More specifically, the method for manufacturing the
laminated core S includes the following steps:
(A) feeding the sheet W drawn from the roll C to the progressive
die 140;
(B) stamping out the workpiece MS in the progressive die 140, the
workpiece MS including the pieces Md aligned in the circumferential
direction with the circumferential part My; and
(C) stacking more than one of the workpieces MS and fastening the
workpieces MS together to obtain the laminated core S.
To begin with, the roll C of the magnetic steel sheet is prepared,
and is mounted on the uncoiler 110. The magnetic steel sheet (sheet
W) drawn from the roll C is fed to the progressive die 140 (step
(A)).
In the progressive die 140, the workpieces MS are serially produced
by performing stamping on the sheet W (step (B)). The step (B) of
this embodiment includes, before forming the workpieces MS by
stamping out the workpieces MS at the outer circumferences, the
following steps in this order:
(b-1) forming an inner opening (through hole Ma and slot holes Ml)
radially inside the circumferential part My;
(b-2) forming the cutting lines Mc across a region configured to be
the circumferential part My; and
(b-3) returning a piece Md1 having been displaced in the thickness
direction of the sheet W to an original position.
Referring to FIGS. 4A to 4F, FIGS. 5A to 5C, and FIGS. 6A to 6C,
the step (B) will be described. FIGS. 4A to 4F are plan views for
illustrating an overall strip layout for stamping serially
performed by the progressive die 140. FIGS. 4A to 4F are plan views
for each illustrating a state of the sheet W after respective steps
B1 to B6 described below are performed. FIGS. 5A to 5C are enlarged
views of FIGS. 4A to 4C, and FIGS. 6A to 6C are enlarged views of
FIGS. 4D to 4F, respectively. The strip layout for stamping is not
limited to that depicted in these drawings, and a step for
balancing press loads or a step of forming a
temporarily-interlocking portion may be added, for example. A step
B1, a step B2, and a step B3 below may be performed in any
order.
The step B1 is a step of forming a total of 12 slot holes Ml on the
sheet W on which pilot holes P have been formed (see FIG. 4A and
FIG. 5A). The pilot holes P are holes for positioning the sheet W
in the progressive die 140.
The step B2 (step (b-1)) is a step of forming the through hole Ma
(see FIG. 4B and FIG. 5B). Performing this step connects the 12
slot holes Ml and the through hole Ma, and forms the inner opening
radially inside the circumferential part My.
The step B3 is a step of forming a total of 12 openings H1 at
positions corresponding to both ends of bending lines Lb to make it
easier to perform cutting-and-bending processing at a next step B4
(see FIG. 4C and FIG. 5C). The openings H1 are formed radially
outside the region configured to be the circumferential part My in
the radial directions of the slot holes M to prevent lines (bending
lines Lb) connecting adjacent two openings H1 from passing through
the circumferential part My. The openings H1 may not be necessarily
formed, but forming the openings H1 at the above-described
positions have the effect of reducing abrasion of a punch used for
cutting-and-bending processing.
An opening H2 may be further formed on the line (bending line Lb)
connecting two openings H1 at both ends of the bending line Lb as
depicted in FIG. 7 to make it further easier to bend the sheet W.
When the opening H2 has a shape having the longitudinal direction
(rectangular or elliptical shape, for example), the longitudinal
direction is preferably aligned with the direction of the bending
line Lb. When the openings H1 at both ends of the bending line Lb
also have a shape having the longitudinal direction (rectangular or
elliptical shape, for example), the longitudinal directions are
also preferably aligned with the direction of the bending line Lb
(see FIG. 7).
The step B4 (step (b-2)) is a step of forming the cutting lines Mc
by cutting-and-bending processing (see FIG. 4D and FIG. 6A). At
this step, the cutting lines Mc are formed by displacing the
overall portion configured to be each piece Md1 of the workpiece MS
downward by a punch (not depicted) positioned above. At this time,
portions (pieces Md2 and Md2) on both sides of the piece Md1 to be
displaced downward are each fixed. Forming the cutting lines Mc in
this manner cuts the piece Md1 off from both adjacent portions. As
depicted in FIG. 6A, a total of 12 cutting lines Mc can be formed
by performing cutting-and-bending processing on a total of 6 every
other pieces Md among the total of 12 pieces Md.
A case has been exemplified here in which the overall portion
configured to be each piece Md of the workpiece MS is displaced
downward by the punch positioned above, but the overall portion may
be displaced upward by a punch positioned below. As long as the
overall portion is displaced in the thickness direction of the
plate for processing by a punch and the cutting lines Mc can be
appropriately formed, an end face Pa of the punch may contact part
of the portion (FIG. 8A), or the end face Pa of the punch may
contact the overall portion (FIG. 8B). The end face Pa of the punch
preferably contacts the overall portion as depicted in FIG. 8B from
a viewpoint of unlikelihood of deformations of the piece Md even
with an increased moving speed of the punch.
A step B5 (step (b-3)) is a step of returning the piece Md having
been displaced in the thickness direction of the sheet W to the
original position (see FIG. 4E and FIG. 6B). This step can be
performed by push-back.
A step B6 is a step of stamping out the workpiece MS at the outer
circumference (step of forming an opening H3) (see FIG. 4F and FIG.
6C). The opening H3 is positioned radially inside the bending lines
Lb. Thus, the region on which the bending lines Lb are formed can
be excluded from the workpiece MS by performing stamping at the
outer circumference of the workpiece MS (circumferential part My).
In this manner, the workpiece MS sufficiently little affected by
effects such as a deformation associated with the formation of the
cutting lines Mc can be obtained.
A predetermined number of the workpieces MS (FIG. 2) obtained
through the above-described steps B1 to B6 are stacked together,
and these workpieces MS are fastened together to give the laminated
core S (step (C)). Any method for fastening the workpieces MS
together is applicable. As described above, methods such as
swaging, welding, adhesive, a resin material, and combinations
thereof may be used as appropriate.
In the foregoing, one embodiment of this disclosure has been
described, but the present invention is not limited to the
above-described embodiment. In the above-described embodiment, a
case has been exemplified in which the cutting lines Mc are formed
by cutting-and-bending processing, but the cutting lines Mc may be
formed by stamping, for example. Referring to FIGS. 9A to 9E, FIGS.
10A to 10C, and FIGS. 11A and 11B, the step (B) of forming the
cutting lines Mc by stamping will be described. FIGS. 9A to 9E are
plan views for illustrating an overall strip layout for stamping
serially performed by the progressive die 140. FIGS. 9A to 9E are
plan views for each illustrating a state of the sheet W after
respective steps B1' to B5' described below are performed. FIGS.
10A to 10C are enlarged views of FIGS. 9A to 9C, and FIGS. 11A and
11B are enlarged views of FIGS. 9D and 9E, respectively. The strip
layout for stamping is not limited to that depicted in these
drawings. The step B1', the step B2', and the step B3' below may be
performed in any order.
The step B1' (step (b-1)) is the same step as the above-described
step B1: a step of forming the total of 12 slot holes Ml on the
sheet W on which the pilot holes P have been formed (see FIG. 9A
and FIG. 10A).
The step B2' is the same step as the above-described step B2: a
step of forming the through hole Ma for the circumferential part My
(see FIG. 9B and FIG. 10B).
The step B3' is a step of forming a total of 12 openings H1' at
positions corresponding to the outer circumference of the workpiece
MS (circumferential edge of the opening H3) radially outside the
slot holes Ml to make it easier to perform stamping at the next
step (step B4) (see FIG. 9C and FIG. 10C).
The step B4' is a step of forming the cutting lines Mc by stamping
and returning by push-back the stamped-out piece Md to the original
position (step (b-2) and step (b-3)). At this step, the cutting
lines Mc are formed by stamping out the overall portion configured
to be the piece Md1 of the workpiece MS by a punch (not depicted).
At this time, portions (pieces Md2 and Md2) on both sides of the
piece Md1 to be displaced downward are each fixed. Forming the
cutting lines Mc in this manner cuts the piece Md1 off from both
adjacent portions. As depicted in FIG. 9D and FIG. 11A, a total of
12 cutting lines Mc can be formed by performing stamping on a total
of 6 every other pieces Md among the total of 12 pieces Md.
Performing this step also forms six cutting lines Mb constituting
part of the outer circumference of the workpiece MS.
The step B5' is a step of stamping out the workpiece MS at the
outer circumference (step of forming an opening H3') (see FIG. 9E
and FIG. 11B). This step cuts the portions of the outer
circumference of the workpiece MS on which the cutting lines Mb are
not formed at the above-described step B4'. Accordingly, the
opening H3' is formed. Also in this manner, the workpiece MS
sufficiently little affected by effects such as a deformation
associated with the formation of the cutting lines Mc can be
obtained as in the above-described embodiment.
In the embodiment depicted in FIGS. 9A to 9E, FIGS. 10A to 10C, and
FIGS. 11A and 11B, a case has been exemplified in which the cutting
lines Mb and the cutting lines Mc are formed by stamping followed
by push-back, but only the cutting lines Mc may be formed by
stamping followed by push-back. Referring to FIG. 12, FIG. 13A, and
FIG. 13B, its specific example will be described. FIG. 12 is a plan
view for illustrating a state of the sheet W before the cutting
lines Mc are formed by stamping. In the state depicted in FIG. 12,
a pair of openings H4a and H4a, an opening H4b positioned
therebetween, and two openings H5 and H5 radially outside these
openings have been further formed on the sheet W depicted in FIG.
4B. FIG. 13A is a sectional view (sectional view along the line a-a
depicted in FIG. 12) for illustrating a state before forming the
cutting lines Mc by stamping, and FIG. 13B is a sectional view for
illustrating a state after forming the cutting lines Mc by stamping
by a descent of a punch Pn. After the state depicted in FIG. 13B,
the stamped-out portion (portion configured to be the piece Md1) is
returned by push-back to the original position.
In FIG. 12, the shape indicated by a long dashed line and a
dot-and-dash line is the shape of the end face Pa of the punch Pn.
In FIG. 12, the shape indicated by the long dashed line and a
dash-dot-dot line is the shape of an opening Da of a die D.
Displacing the punch Pn downward (see FIG. 13B) forms the
respective cutting lines Mc between the portion configured to be
the piece Md1 and portions (portions configured to be the pieces
Md2 and Md2) on both sides. The two cutting lines Mc are formed
across the region configured to be the circumferential part My. In
FIG. 12, a short dashed line indicates the position of the outer
circumference (opening H3) of the workpiece MS.
The openings H4a, H4b, and H5 depicted in FIG. 12 are intended to
reduce the strength of the region radially outside the region
configured to be the workpiece MS. The region of low strength is
formed radially outside the region configured to be the workpiece
MS, so that the region of low strength stretches as depicted in
FIG. 13B when stamping is performed by the punch Pn. This
stretching can sufficiently reduce the effect of stamping remaining
in the workpiece MS. In addition, since the piece Md1 is not
entirely stamped out by stamping but the portion configured to be
the piece Md1 is connected to the rest of the sheet W via the
region of low strength, push-back can be more stably and reliably
performed. Furthermore, the end face Pa of the punch Pn may be a
surface orthogonal to the moving direction of the punch Pn in
stamping, while cutting-and-bending processing requires the end
face of the punch to be a tilted surface, for example.
As depicted in FIG. 12, the pair of openings H4a and H4a and the
opening H4b therebetween are formed along the outer circumference
of the workpiece MS radially outside the region configured to be
the workpiece MS. The positions of these openings H4a, H4a, and H4b
are preferably aligned with part of the outer circumference
(dot-and-dash line in FIG. 12) of the end face Pa of the punch Pn.
The pair of openings H4a and H4a are formed at positions
corresponding to corners of the end face Pa of the punch. Forming
the openings H4a at these positions can reduce abrasion of the
punch Pn used for stamping. The opening H4b is formed between the
pair of openings H4a and H4a. Portions 4c between the openings H4a
and the opening H4b preferably have sufficient strength to keep
from breaking during stamping. Equal to or more than two openings
H4b may be formed between the pair of openings H4a and H4a.
The two openings H5 and H5 are formed along the openings H4a, H4a,
and H4b radially outside the openings H4a, H4a, and H4b and
radially inside the outer circumference (portion of the
dash-dot-dot line depicted in FIG. 12 extending along the
circumferential direction) of the opening Da of the die D. The
openings H5 extend from points positioned radially outside the
portions 4c between the openings H4a and the opening H4b toward
both circumferential directions (right and left directions in FIG.
12). Forming the openings H5 at such positions results in
"T-shaped" portions on the sheet W formed by the openings H5, the
openings H4a, and the opening H4b (see FIG. 12). The distance
(width w in FIG. 13A) between the openings H5 and the opening H4b
(or the openings H4a) may be about 1 to 5 times as large as the
thickness of the sheet W. When the width w is equal to or larger
than the thickness of the sheet W, breaking of the portion during
stamping is sufficiently prevented. When the width w is equal to or
less than 5 times larger than the thickness, the portion
preferentially deforms during stamping, thereby sufficiently
reducing the effect of stamping remaining in the workpiece MS. The
number of the openings H5 is not limited to two but may be equal to
or more than three. The positions of the openings H5 in the radial
direction may be aligned with the position of the outer
circumference of the opening Da of the die D.
Also in the above-described embodiments, the overall portion
configured to be the piece Md1 is displaced in the thickness
direction of the sheet W, with portions configured to be pieces Md
on both sides of the piece Md1 being fixed, to form the two cutting
lines Mc.
In the above-described embodiments, cases have been exemplified in
which one core piece Sd has one tooth part St, but one core piece
Sd may have a plurality of tooth parts St. FIG. 14 is a plan view
of a laminated core including eight core pieces Sd each having six
tooth parts St.
In the above-described embodiments, cases have been exemplified in
which the workpiece MS including 12 (an even number of) pieces Md
is produced, but the method according to this disclosure may be
applied to production of a workpiece including an odd number of
pieces Md. FIG. 15 is a plan view of a workpiece including nine
pieces Md. To produce the workpiece depicted in FIG. 15,
cutting-and-bending processing (or stamping) is first performed on
three pieces Md indicated by coarse hatching among the nine pieces,
whereby cutting lines Mc1 are formed on both sides of the
respective three pieces Md. Then, cutting-and-bending processing
(or stamping) is performed on three pieces Md (pieces indicated by
dense hatching) adjacent to the coarsely hatched three pieces Md,
whereby cutting lines Mc2 are formed on one side of each of the
densely hatched three pieces Md. The workpiece including nine
pieces Md can be obtained through these steps. In other words, when
a workpiece including an odd number of pieces Md is to be produced,
the segmented workpiece can be produced by performing
cutting-and-bending processing or stamping on portions configured
to be pieces Md sandwiching a plurality of portions configured to
be pieces Md of a constant number depending on the number of the
pieces Md.
In the above-described embodiments, cases have been exemplified in
which the openings H1 or the openings H1' are formed to reduce
abrasion of the punch before cutting-and-bending processing or
stamping to form the cutting lines Mc, but the openings H1 and the
openings H1' may not be necessarily formed.
In the above-described embodiments, cases have been exemplified in
which the laminated core S that includes the tooth parts St
extending from the inner periphery of the yoke part Sy toward the
center is produced, but the method according to this disclosure may
be applied to production of a laminated core (of an outer rotor
type, for example) that includes tooth parts St extending
outward.
Cases have been exemplified in which the bending lines Lb are
formed radially outside the circumferential part My (see FIG. 6A),
but the bending lines Lb may be formed radially inside the
circumferential part My. In this case, a segmented workpiece can be
produced through the following steps. That is, stamping at the
outer circumference is first performed only on a piece Md to be
subjected to cutting-and-bending processing to enable the overall
piece Md to be subjected to cutting-and-bending processing to be
displaced in the thickness direction of the sheet W. Then, the
cutting lines Mc are formed by displacing the overall piece Md with
the bending line Lb positioned radially inside being the fulcrum.
After forming the cutting lines Mc by cutting-and-bending
processing, the through hole Ma may be formed (stamping at the
inner circumference), and the opening H3 may be formed (stamping at
the outer circumference).
In the above-described embodiments, cases have been exemplified in
which only the workpieces MS are stamped out of one sheet W, but
both of the workpieces MS and the workpieces for a rotor may be
stamped out of one sheet W. Furthermore, the workpieces may be
stamped out of a plurality of stacked plates for processing W.
In a method disclosed in Japanese Patent No. 4472417, there is room
for improvement in the following point. That is, when forming slit
lines L by cutting-and-bending processing, this method also forms
bending lines across a region configured to be a yoke part of a
laminated core (see FIG. 7 in Japanese Patent No. 4472417). The
method has the problem that a deformation or stress caused by
cutting-and-bending processing is likely to remain in the yoke part
even after pushing back the bent portions (part of the yoke part)
after cutting-and-bending processing.
A plurality of embodiments of this disclosure has an object to
provide a method for manufacturing a workpiece (hereinafter
referred to as "segmented workpiece" in some cases) for a segmented
laminated core sufficiently little affected by effects such as a
deformation associated with the formation of cutting lines for
segmenting the workpiece into a plurality of pieces. In addition, a
plurality of embodiments of this disclosure has an object to
provide a method for manufacturing a laminated core from a
plurality of segmented workpieces produced by this manufacturing
method.
One aspect of this disclosure relates to a method for manufacturing
a segmented workpiece. This manufacturing method includes (A)
feeding a plate for processing drawn from a roll thereof to a
progressive die and (B) stamping out a workpiece in the progressive
die, the workpiece including a plurality of pieces aligned in the
circumferential direction with a circumferential part. At the
above-described step (B), an overall portion configured to be each
piece of the workpiece is displaced in a thickness direction of the
plate for processing, with portions on both sides of the piece
being fixed, to form at least one cutting line across a region
configured to be the circumferential part.
In a plurality of embodiments of this disclosure, an overall
portion configured to be a piece of the workpiece is displaced in
the thickness direction of the plate for processing to form the
cutting lines. Since the overall portion configured to be a piece
of the workpiece is displaced, a deformation and the like
associated with the formation of the cutting lines remaining in the
piece can be sufficiently reduced.
When forming the cutting lines, the cutting lines may be formed by
(1) cutting-and-bending processing or (2) stamping, as long as the
overall portion configured to be the piece of the workpiece is
displaced in the thickness direction of the plate for processing in
the mode of the invention.
(1) When the Cutting Lines are Formed by Cutting-and-Bending
Processing
Cutting-and-bending processing may form at least one cutting line
and form a bending line radially outside or inside the
circumferential part (see FIG. 6A). Since the bending line is
formed radially outside or inside the circumferential part, a
region on which the bending line is formed through a process of
producing the workpiece can be excluded from the workpiece. Thus,
the workpiece sufficiently little affected by effects such as a
deformation associated with the formation of the cutting line for
segmenting the workpiece into a plurality of pieces can be
obtained.
(2) When the Cutting Lines are Formed by Stamping
Stamping may form at least one cutting line (see FIG. 11A). When
the cutting line cannot be formed alone by stamping, part of the
outer circumference or the inner circumference of the workpiece may
be formed together with the cutting line. The overall portion
configured to be the piece of the workpiece is displaced in the
thickness direction of the plate for processing to form the cutting
line, so that no bending line is formed on the piece. Thus, the
workpiece sufficiently little affected by effects such as a
deformation associated with the formation of the cutting line for
segmenting the workpiece into a plurality of pieces can be
obtained.
From a viewpoint of efficiently producing a segmented workpiece,
the above-described step (B) may include, before forming the
circumferential part of the workpiece by stamping out the workpiece
at the outer circumference, (b-1) forming a through hole for the
circumferential part and (b-2) forming the plurality of cutting
lines radially extending on the circumferential part so that the
workpiece will be segmented into a plurality of pieces aligned in
the circumferential direction, in this order. The above-described
step (B) may further include, after the above-described step (b-2),
(b-3) returning the piece having been displaced in the thickness
direction of the plate for processing to an original position. The
piece having been displaced is returned to the original position by
push-back in the progressive die, for example, thereby producing,
with the progressive die, the workpiece in which the pieces aligned
in the circumferential direction are connected.
A method for manufacturing a laminated core according to one aspect
of this disclosure includes producing workpieces by the
above-described manufacturing method and fastening the workpieces
together to obtain a laminated core. The laminated core produced by
the method includes the workpieces sufficiently little affected by
effects such as a deformation and thus has sufficiently good
magnetic properties. Any method for fastening the workpieces
together is applicable. For example, the workpieces may be fastened
to each other by swaging, welding, adhesive, or a resin
material.
With a plurality of embodiments of this disclosure, a workpiece for
a segmented laminated core sufficiently little affected by effects
such as a deformation associated with the formation of cutting
lines for segmenting the workpiece into a plurality of pieces can
be obtained.
Indeed, the novel devices and methods described herein may be
embodied in a variety of other forms; furthermore, various
omissions, substitutions and changes in the form of the devices and
methods described herein may be made without departing from the
spirit of the inventions. The accompanying claims and their
equivalents are intended to cover such forms or modification as
would fall within the scope and spirit of the inventions.
* * * * *